// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2016 Google Inc. All rights reserved.
// http://ceres-solver.org/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
//   this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
//   this list of conditions and the following disclaimer in the documentation
//   and/or other materials provided with the distribution.
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//   used to endorse or promote products derived from this software without
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//
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// POSSIBILITY OF SUCH DAMAGE.
//
// Author: vitus@google.com (Michael Vitus)
//
// Reads a file in the g2o filename format that describes a pose graph problem.

#ifndef EXAMPLES_CERES_READ_G2O_H_
#define EXAMPLES_CERES_READ_G2O_H_

#include <fstream>
#include <string>

inline std::istream& operator>>(std::istream& input, Pose3d& pose) {
	input >> pose.p.x() >> pose.p.y() >> pose.p.z() >> pose.q.x() >> pose.q.y() >>
		pose.q.z() >> pose.q.w();
	// Normalize the quaternion to account for precision loss due to
	// serialization.
	pose.q.normalize();
	pose.s = 1.0;
	return input;
}


inline std::istream& operator>>(std::istream& input, Constraint3d& constraint) {
	Pose3d& t_be = constraint.t_be;
	input >> constraint.id_begin >> constraint.id_end >> t_be;
	constraint.information.setZero();

	for (int i = 0; i < 6 && input.good(); ++i) {
		for (int j = i; j < 6 && input.good(); ++j) {
			input >> constraint.information(i, j);
			if (i != j) {
				constraint.information(j, i) = constraint.information(i, j);
			}
		}
	}
	return input;
}

// Reads a single pose from the input and inserts it into the map. Returns false
// if there is a duplicate entry.
template <typename Pose, typename Allocator>
bool ReadVertex(std::ifstream* infile,
	std::map<int, Pose, std::less<int>, Allocator>* poses) {
	int id;
	Pose pose;
	*infile >> id >> pose;

	// Ensure we don't have duplicate poses.
	if (poses->find(id) != poses->end()) {
		std::cout << "Duplicate vertex with ID: " << id << std::endl;
		return false;
	}
	(*poses)[id] = pose;

	return true;
}

// Reads the contraints between two vertices in the pose graph
template <typename Constraint, typename Allocator>
void ReadConstraint(std::ifstream* infile,
	std::vector<Constraint, Allocator>* constraints) {
	Constraint constraint;
	*infile >> constraint;

	constraints->push_back(constraint);
}

// Reads a file in the g2o filename format that describes a pose graph
// problem. The g2o format consists of two entries, vertices and constraints.
//
// In 2D, a vertex is defined as follows:
//
// VERTEX_SE2 ID x_meters y_meters yaw_radians
//
// A constraint is defined as follows:
//
// EDGE_SE2 ID_A ID_B A_x_B A_y_B A_yaw_B I_11 I_12 I_13 I_22 I_23 I_33
//
// where I_ij is the (i, j)-th entry of the information matrix for the
// measurement.
//
//
// In 3D, a vertex is defined as follows:
//
// VERTEX_SE3:QUAT ID x y z q_x q_y q_z q_w
//
// where the quaternion is in Hamilton form.
// A constraint is defined as follows:
//
// EDGE_SE3:QUAT ID_a ID_b x_ab y_ab z_ab q_x_ab q_y_ab q_z_ab q_w_ab I_11 I_12 I_13 ... I_16 I_22 I_23 ... I_26 ... I_66 // NOLINT
//
// where I_ij is the (i, j)-th entry of the information matrix for the
// measurement. Only the upper-triangular part is stored. The measurement order
// is the delta position followed by the delta orientation.
template <typename Pose,
	typename Constraint,
	typename MapAllocator,
	typename VectorAllocator>
	bool ReadG2oFile(const std::string& filename,
		std::map<int, Pose, std::less<int>, MapAllocator>* poses,
		std::vector<Constraint, VectorAllocator>* constraints) {

	poses->clear();
	constraints->clear();

	std::ifstream infile(filename.c_str());
	if (!infile) {
		return false;
	}

	std::string data_type;
	while (infile.good()) {
		// Read whether the type is a node or a constraint.
		infile >> data_type;
		if (data_type == Pose::name()) {
			if (!ReadVertex(&infile, poses)) {
				return false;
			}
		}
		else if (data_type == Constraint::name()) {
			ReadConstraint(&infile, constraints);
		}
		else {
			std::cout << "Unknown data type: " << data_type << std::endl;
			return false;
		}

		// Clear any trailing whitespace from the line.
		infile >> std::ws;
	}

	return true;
}

#endif  // EXAMPLES_CERES_READ_G2O_H_